Not applicable.
1. Field of the Invention
This invention relates to a positive displacement pump which allows a liquid additive to be introduced into another liquid stream (such as water coming from a faucet) and mixes the liquids together in a constant proportion without the use of any external power source.
2. Description of the Related Art
The prior art in this field contains many methods for injecting fertilizer or the like into a water stream. Some of these devices utilize an external power source to inject fertilizer into a water supply. Other pumps rely on small pressure drops in the lines to inject fertilizer. These are often referred to as Venturi-type injectors. Unfortunately, such devices do not allow for exact dimensioning of liquid fertilizer into the water stream. Often, the liquid fertilizer additive is not kept in a constant proportion to the irrigation water flow through the supply line. Further, these devices cannot operate against back pressure which is created by a length of hose.
Other known systems for injecting liquid fertilizer into a pipe carrying irrigation water include systems consisting of an axial turbine impeller coaxially positioned in the pipe and a pump in the form of a helical rotor rotating within a flexible stator housing. A valve means is provided for controlling the fertilizer flow. The main drawback of this system is the low efficiency of the helical pump due to its enclosure in a flexible stator housing causing considerable friction losses.
Another known embodiment of a fertilizer injector comprises a tangential turbine and a pump mounted on a common shaft in a casing positioned outside an irrigation pipe. The turbine is driven by a measured flow of water drawn from the pipe and spilled into the open after having passed the turbine. The pump draws fertilizer out of a container and injects it into the pipe downstream of the port delivering water to the turbine. Two kinds are proposed as alternatives: (1) a spiral-type screw conveyor and (2) a centrifugal impeller. Both kinds of pumps are enclosed in a casing which communicates at its low-pressure side with a fertilizer container, and at its high-pressure side with the irrigation pipe. This system suffers from the drawback that the used water is spilled into the open, and that the pump-impeller is necessarily of low efficiency.
Another embodiment of a fertilizer injection system comprises an axial-flow turbine impeller coaxially positioned in the irrigation pipe, a gear pump positioned outside the pump on the mounting plate, and a gear train extending between turbine and gear pump. Again, as in the aforementioned systems, the pump injects liquid into the pipe carrying the irrigation water. The main drawback of this embodiment is the requirement of bevel gearing for transmission of power from turbine to pump, which is usually a source of trouble, especially as the gear is submerged in the water in the pipe and is not readily accessible.
There are also many other methods for injecting a liquid additive (not necessarily liquid fertilizer) to a water stream. One involves water passing through a pipe, turning a water wheel, and then flowing out to another pipe. The rotation of the water wheel through a shaft causes rotation of a soap wheel. When the soap wheel is rotated, soap passes down from the reservoir into the recess in the body and thus to the top of the soap wheel which receives soap between its teeth and carries the soap around in the recess in the body to a position in line with the pipe in which the water is discharged. As the water passes the periphery of the soap wheel, it picks up water and discharges it through the tube as suds.
Other devices consist of an axial turbine impeller rotatably positioned in housing. Liquid fertilizer is caused to enter the inlet through an inlet port in the housing, is pressurized by the movement of vanes along the channel and leaves the outlet end through an outlet port in the housing, from where it is conveyed to the irrigation pipe at a point downstream of the pump impeller.
Yet another device utilizes a pump with a main fluid chamber (water chamber) and an additive fluid chamber. In the main fluid chamber, a pair of multivaned impellers are rotatably mounted and inter-engaged intermediate the inlet and outlet. The additive fluid chamber is spaced from the main fluid chamber and has similarly mounted impellers which are axially aligned with the impellers of the main fluid chamber and secured rotatably by said main fluid chamber impellers. The outlet of this additive fluid chamber is connected in fluid communication with a diffuser in the main fluid chamber, said diffuser being positioned midway of said impellers in the main fluid chamber. The impellers of the additive fluid chamber are formed for passing fluid through said chamber of a determined, proportional volume less than the fluid passed through said main fluid chamber by the impellers thereof. Thus, additive fluid will be metered into the main fluid chamber for mixing with the main fluid flow in determined and exact proportion.
Finally, several devices for injecting solid fertilizer into a pipeline carrying water have been disclosed in the prior art. In these devices, a cover for a casing is usually removed and a certain amount of water-soluble material is added. Then, the casing is closed and the water supply is started. The water is directed onto the blades and the material inside the container is pressed against the inner surface of the peripheral wall as a result of the centrifugal or rotational force. Only completely dissolved material in the water can leave the interior of the container due to the centrifugal force pressing the undissolved material against the inner surface of the container""s peripheral wall. Obviously, the main drawback of this device is the requirement that a solid fertilizer be loaded into the casing prior to each use.
The present invention has as its main objective the avoidance of the above-mentioned drawbacks.
It is a further object of the invention to provide a cheap and reliable pump which delivers a steady stream of water/fertilizer mixture (or other mixture of liquids) of a constant concentration.
Yet another object of the invention is to create a pump which will work against back pressure created by a length of hose attached to the end of the pump. This will allow the pump to be connected directly to a faucet rather than to the end of a garden hose. This also allows a liquid fertilizer reservoir to be placed next to the faucet rather than lugged to the middle of the lawn near the sprinkler during each use. Further, the present invention should be easily installed and capable of remaining on the faucet even when the faucet is being used to generate a pure water stream.
In general, the present invention involves a pump which can be connected to a faucet at its top end and connected to a typical garden hose or other device at its bottom end. Water enters the pump through a faucet and is redirected (bent) by vanes on a stator which allows the water to enter the turbine at an optimal angle to rotate the turbine impellers. The turbine is rotatably connected to a cam which allows the cam to move pistons. The movement of the pistons allows liquid fertilizer to be drawn from its reservoir when the valve connecting the liquid fertilizer reservoir to the pump is in an open position. The liquid fertilizer flows through an inlet tube into the piston and then into the exit tubes through the motion of the pistons. The liquid fertilizer combines with the water to create a water/fertilizer mixture which then flows through the hose to an attached sprinkler or other device.
It is important to note that although this invention is often discussed as a pump for mixing liquid fertilizer with water, it actually has many other potential uses. In reality, the present invention can be used to combine any liquid with a constant stream of any other liquid to form a uniform mixture.